ESAY 2.1

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Chapter 2.1

Vocabulary


Earthquake:shaking/trembling of rocks underneath Earth's surface
Stress:the force that acts/pushes on a rock to change it
Shearing:form of stress that pushes two large pieces of rock in opposite directions
Tension:form of stress that pulls apart a rock so that the middle is thinner than that of the sides/edges
Compression:form of stress that squeezes rock until it folds or breaks
Deformation:change of volume or shape in Earth's crust
Fault:a place where two rocks have slipped past each other
Strike-slip Fault:a fault where two rocks have slipped past each other with very little to no up-down motion
Normal Fault: a normal fault is at an angle, so that one side is on top, and the other is on the bottom
Reverse Fault:similar structure to a normal fault except for that they move differently
Fault-block mountain: A mountain that forms where a normal fault lifts a block of rock.
Fold: A bend in rock that forms where part of the Earth's crust is compressed.
Anticline: A fold in the rock that bends upward
Syncline: A fold in the rock that bends downward
Plateau: A large area of flat land elevated high above sea level.


Outline



Stress in the Crust


  • An earthquake is the shaking and trembling of rock beneath surface.
  • This movement of earth creates powerful forces that squeeze or pull the rock in the crust.
  • These forces are examples of stress, that forces the rock to change its shape or volume.
  • The three types of stress are shearing, tension, and compression.

Kinds of faults
  • A fault usually occurs along the plate boundaries, where forces of plate motion compress, pull, or shear the crust so much that the crust breaks.
  • There are three types of faults. Strike slip faults occur when two two rocks on either side of the fault slip past each other.
  • A normal fault is when the fault is at an angle, where one block of rock lies below the fault.A reverse fault has the same structure of a normal fault, but the block moves in opposite direction.

Friction along faults
Friction is the force that opposes the motion of one surface as it moves across another surface.
  • The San Andreas fault in California forms a transform boundary between the pacific plate and the North American plate.
  • In most places among the San Andreas fault, friction is high and the stress builds up until an earthquake releases the stress and the plates slide past each other.

Mountain Building

The forces of plate movement can build up earths surface.
  • Over millions of years, fault movement can change a flat plain into a towering mountain range.
  • When a normal fault uplifts a block of rock, a fault-block mountain is formed. The Sierra Nevada of california is a fault-block mountain range.
  • Under certain conditions plate movement cause the crust to fold. The collision of two plates can cause compression and folding of the crust.
  • The Himalayas in Asia and the Alps in Europe were formed when pieces of the crust folded during the collision of two plates.

Anticlines and Synclines

Geologists use the terms anticline and synclines to describe upward and downward folds in rock.
  • A fold in the rock that bends upward is called anticline.
  • A fold in the rock that bends downward is called syncline.

Plateau

The force that raises mountains can also raise plateaus.
  • A plateau is a flat land elevated high above sea level.
  • A plateau consists of many layers of rock.
  • The kaibab plateau forms the north rim of the Grand Canyon in Arizona.






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